The present invention relates to a method and apparatus for determining an optical signal-to-noise ratio (OSNR) penalty in an optical network. The OSNR penalty serves as a measure for a quality of an optical signal transmitted via an optical link between a source optical node and a destination optical node
In transparent optical networks, the optical signal quality is affected by different impairments like chromatic dispersion (CD), amplifier stimulated emission (ASE) noise, crosstalk, polarization mode dispersion (PMD), self-phase modulation (SPM), cross-phase modulation (XPM), four wave mixing (FWM), etc. When optical networks are designed, the operators need to have knowledge about the network behavior, for example, dimension geographical positions of network nodes, distance between network nodes, signal launching powers, amplifier spans, number of amplifiers and further network related parameters. Therefore, it is important to predict the signal quality even before the signal is set up. In order to evaluate the signal quality, there are generally two ways:
One way is based on full numerical simulation by solving the nonlinear Schrödinger equations for signal transmission in optical fibers. However, this method takes too much time, which cannot fulfill the time requirements for fast network design and real time signal quality evaluation.
The other way is to abstract some parameters for the transmission link and to represent the signal quality by these parameters with some functions.